Sliding coaxial switch



y 9 1 s. G. GREENE 2,550,921

SLIDING cQAxIAL swrrcn Filed Aug. 11, 1948 a; E a? 201 Patented May 1,1951 SLIDING COAXIAL SWITCH Gardiner G. Greene, Newton, Mass., assignorto The Workshop Associates, Incorporated, Newton Highlands, Mass., acorporation of Massachusetts Application August 11, 1948, Serial No.43,603

8 Claims.

In high frequency communication systems it is often desirableconsecutively to establish connection, through a wave guide channel,between selected components of several groups of circuit elements. Suchelements are for example those of the antenna, on the one hand andreceiver or transmitter of television and frequency modulation systemson the other hand. To eliminate reflected waves, it is a common practiceto couple the antenna and receiver by means of a coaxial cable having acharacteristic impedance which is substantially the same as that of theconnected antenna. The matching of the characteristic impedance of thereceiving elements introduces difiiculties when, for example for salesdemonstration purposes, several receivers are to be successivelyconnected to the same antenna, or conversely when, to improve signalstrength, a receiver is selectively connected to one of a plurality ofreceiving antennas.

Objects of this invention are to provide a switch" number of lines,which is economical to construct, and which advances the art of switchmanufacture generally.

In a broad aspect the invention contemplates a multi-position switchcomprising a hollow con- 8' .5 ing a plurality O1" coaxial connectorseach having a projectin contact extending within the body used to couplethe switch to the respective coaxial lines. A connector is centricallylocated in one or each of the end plates, the remaining connectors beingpositioned in the wall of the body. A movable assembly is supportedwithin the body and electrically connected to the projecting contact ol'the end plate connector. This assembly includes an operating means and amovable arm for selectively making contact with the respectiveprojecting contacts of the wall connectors. The configurations of thebody and movable assembly are dimensioned relatively to each other sothat the characteristic impedance of the switch is of substantially thesame magnitude as that of the connected lines.

In one specific aspect the switch according to the invention comprises aholfow body having a cylindrical wall, the ends of which are closedrespectively by two end plates and a plurality of connectors forcoupling the switch with the re- I spective coaxial lines.

, tive connectors located in the end plates.

ductive body having an opening which is closed .by a plate, a pluralityof coaxial lines leading into the body having their outer tubularconductors conductively connected to the body and a coaxial linehavingits outer tubular conductor mounted on the plate, with the ends of theinner conductors extending into the body, an assembly movable within thebody having a conductive connecting portion irictionally engaging theinner conductor which is mounted on the plate and a contact portionconductingly joined to the connecting portion and resiliently fittingthe end of each one of the inner conductors which extend into the body,and an actuator for switch 7 ing the contact portion between adjacentinner of the above indicated type has a cylindrical wall with its endsclosed by end plates and support- A connector is positioned in a taperedaperture centrically located in the inner surface of each of therespective end plates. The remaining connectors are positioned in thebody wall in a plane passing through the axis thereof. A cylindricalmember is supported coaxially within the body wall. Each end of themember is conically shaped with a hole in the apex thereof for engaginga contact pin projecting into the interior of the body from the respec-A slidable assembly is supported within the body upon the cylindricalmember so that a recess in one end of a movable contact arm selectivelymakes with the respective contact pins projecting within the body fromthe wall connectors. The other end of the contact arm is fastened to anoperatend of the cylindrical wall is closed by an end plate having atapered aperture wherein is centrically located a connector. Aninsulating cover plate, having a recess wherein is supported one end ofthe cylindrical member, closes the opposite end of the wall. The otherend of the member is conically shaped with a hole in the apex thereoffor engaging the contact pin of the end plate A slidable assembly issupported within the body upon the cylindrical member so that a recessin one end of a movable contact arm selectively makes with therespective contact pins projecting from the wall connectors. The otherend of the contact arm is fastened to an operating handle which projectsout through a slot located in the body wall diametrically opposite thewall connectors. A spring loop is interposed between the ends of thecontact to insure adequate electrical contact pressure. I

In all these embodiments the relative diametersor the wall and thecylindrical member and the relative tapers of the end plate and the endof the cylindrical member are proportioned so that the characteristicimpedance of the switch is of substantially the same magnitude as thatof the connected coaxial lines.

These and other objects and aspects of the invention will be apparentfrom the typical embodiment thereof illustrated in the accompanyingdrawing in which: v h

Fig. 1 is a side elevation view of one embodiment of the invention; I

Fig. 2 is an end elevation 'view of the same embodiment;

3 is a cross sectional view on line 3 -4 of Fig. 2; v

Fig. '4 is a cross sectional view on line 4-4 otFigl; Fig. 5 is anenlargedfragmentary cross sec-- tional view of the slidable assembly;

Fig. Bis a cross sectional view on the line 6'6 hf. Fig.5; and v Fig 7is a fragmentary cross sectional view "or another embodiment of p theinvention;

The body of the switch "shown in Fig. 1 cornprises a cylindrical Wall 12each end of which is closed by a respective end plate M secured byihe'screivs l5. Located in a tapered 'aperture centrically positioned ineach'of the respective end plates I4 is a flangednipple i1 ofaconventional coaxial connector I8. A checknilt Ill ecures each of theconnectors l8 in their i' ective aperture H5. The taper of the sidewalls f each of the apertures I'fi ispro p'o rtioned 'in a manner to bedescribed in'detail'hereinafte'r.

A plur 'ality of similar connectors 2'! are secured in the wall 1'2 in aplane passing through the wall axis. These connectors "2! are secured bycheck nuts in a manner analogous to that hywhich the connectors I8 aresecured in the end plates 14. Although four connectors 2| are showninfigs. 1 and 3,,it will beund'erstoo d that "o .e of the principaladvantages of this type of switch jisjthat by suitably increasing thelength hi the wall 12, any. desired "number of connectors 2'1 canbesecured therein. 7 p

A plurality of contact pins 22, each of, which is electrically connectedto the central conductor "of the respective connector 21, projectswithin the interior of the switch body. A similar contact pinffifiprojects from each of the respective end plate connectors l8 to. supporta cylindrical conducting member 26. The pins 23 can be formed as anintegral extension of the tapered 'ends 24 of the cylindrical member 26;

A slidable assembly 23 (shown in detail in Figs fl, 5 and '6) is movablysupported upon the cylindrical member 26 so that its contact arm 21selectively makes with the respective pins 22 which project from thewall connectors 21. The

' a'rm g7: comprises two identical strip pieces 29 of berryllium bronze'or other material having similar characteristics, maintained in juxtaposed relationship by means of the rivets 3| and 32. The rivets 32 alsopass through the end of the extension 33 of a nonconducting operatinghandle assembly 34. The portion of each piece 29 between the rivets 32and 3| is formed in the shape of a semicircle so that surface to surfacecontact is made with the cylindrical member 26. As is best shown in Fig.6, the ends of each piece 2-!) abutting the contact pin 22 are in theshape of a double ogee, the recess 36 formed thereby cooperating withthe similar recess -of the juxtaposed piece to provide a detent. Theportion of each piece 29 located between the og efe shaped end and therivet 3| is of reduced width and is bent to form a spring loop 35-,thereby insuring both the proper locking action of the detent andproviding adequate electrical contact pressure.

The handle extension 33 projects through a slot 31 cut in thecylindrical wall l2 diametrically opposite the wallconnectors 2i. Moldedintegrally with the extension 33 is a knob 38 curved generally toconform with theouter contour of the wall 12 and having a projectionwhich can begrasp'ed by the fingers-of an operator to move the slidableassembly '28.

To match the characteristic impedance 20 of theconnecting lines thedimensions of the switch must be proportioned so that Zo /L/C where Land C are the distributed inductance and capacitance per unit lengthrespectively;

As the dielectric 'constant of air is unity; the relation of thediameters of the cylindrical member 26'andthe wall 12 are given by theformula zi -138 logi' -D/d. where D is the inner diameter of the outerconductor; and cl is the outerdia-meter oftheinner conductor v The sirfacejtof each of the etaieces 1'4 is tapered'relatively to the taper,of the eerie lated conical e n"d 2" 4 of the"'cylindrical Yn'e'rnhr v.."6 so that "any point "on one of the tapered surfaces liesfin thecircumference of a t rircleii'i a plane normal to the axis "of the ebnef'orm'ed by such surfaceand having adiameter prepaition'ed with respectto the. diameter of ajcircle concentric and coplanar with-the firstcircle and passing throughthe pointfon the other tapered surface closestto the point on the -first*tapered *s nrface whereby the ratio ofdiameters when substituted-in the abovc fo'rmula results in the desiredcharacteristic impedance.

It isals'o "within the scope of this invention to provide a switch witha connector IBf'in one end-only. With such an arrangement, theop- 'posite end of the wall i2 is closed as is shown in Fig, 7 by aninsulating cover 'plat'e. 13. In this embodiment the 'end of thecylindrical member 26 engages a recess 2 1 'inthe cover plate 13 sothattlie'inernber 25 is supported coaxially with 'respecttothe inner'surfacejof the wall '12, The j'constructionbf the remainder of theswitch is identical with that of the first "embodiment, the

location of the wall connectors :21 and the'd ebranch leads areselectively to be connected to the' end of a main lead, the andconnector [8 of a switch such as shown in Fig. 6 is connected to the endof the main line.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includesall modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A multiposition switch for selectively connecting a plurality ofcoaxial lines comprising a hollow body having an end plate and acylindrical wall with an end closed by the plate, a

- plurality of coaxial connectors for couplin said switch to therespective lines, each of said connectorshaving a projecting contactextending within said body, one of said connectors being centricallylocated in the end plate, the remaining connectors being positioned insaid wall in a plane through the wall axis, a supporting member mountedwithin said body by the projecting contact of the end plate connector,and a slidable assembly carried by said supporting member and includingoperating means and a movable contact arm for selectively making withthe respective projecting contacts of the wall connectors, the dimensionof the wall and the supporting member being proportioned relatively toeach other so that the characteristic impedance of the switch is ofsubstantially the same magnitude as that of the connected lines.

2. A multiposition switch for selectively con.- necting a plurality ofcoaxial lines comprising a hollow body having an end plate with atapered aperture centrically located in the inner surface thereof and acylindrical wall with an end closed by the plate, a plurality of coaxialconnectors for coupling said switch to the respective lines, each ofsaid connectors having a projecting contact extending within said body,one of said connectors being located in the tapered aperture of the endplate, the remaining connectors being positioned in said wall in a planethrough the wall axis, a cylindrical member having a conically shapedend abutting the projecting contact of the end connector, and a slidableassembly supported within said body and including operating meanextending through the body wall, and a movable contact arm positionedcircumjacent the cylindrical member for selectively making with therespective projecting contacts of the wall. connectors, the taper ofsaid aperture and said cylindrical member being proportioned relativelyto each other so that the characteristic impedance of the switch is ofsubstantially the same magnitude as that of the connected lines.

3. A multiposition switch for selectively connecting a plurality ofcoaxial lines comprising a hollow body having an end plate and acylindrical wall with an end closed by the plate, a plurality of coaxialconnectors for coupling said switch to the respective lines, each ofsaid connectors having a projecting contact extending within said body,one of said connectors being centrically located in the end plate, theremaining connectors being positioned in said wall in a plane throughthe wall axis, a cylindrical memb'er having a conically shaped endabuttin the projecting contact of the end connector, and a slidableassembly supported within said body and including operating meansextending through the body wall and a movable contact arm forselectively making with the respective projecting con.- tacts of thewall connectors, the end of each projecting contact of the respectivewall connectors being spaced from-the cylindrical member so that thecharacteristic impedance of the switch is of substantially the samemagnitude as that of the connected lines.

4. A multiposition switch for selectively connecting a plurality ofcoaxial lines comprising a hollow body having two end plates, and acylind ical wall with a longitudinal slot therein, the ends of said wallbeing closed by the respective plates; a plurality of coaxial connectorsfor coupling said switch to the respective lines, each of saidconnectors having a projecting contact pin extending within said body,one of said connectors being centrically located in each of therespective end plates, the remaining connectors being positioned in saidwall in a plane passing through both the wall slot and the wall axis; acylindrical member having conically shaped ends, each with a hole in theapex thereof for engaging the contact pin of the respective end plateconnectors; and a slidable assembly supported within said body includingan operating handle with'one" end extending through the wall slot, and amovable contact arm fastened to the opposite handle end and slidablyengaging said cylindrical member for selectively makin with therespective projecting contacts of the wall connectors.

5.--A multiposition switch for selectively connecting a plurality ofcoaxial lines comprising a hollow body having an end plate, a coverplate of insulating material having a recess therein and a cylindricalwall having a longitudinal slot therein, the ends of said wall beingclosed by the respective plates; a plurality of coaxial connectors forcoupling said switch to the respective lines, each of said connectorshaving a projecting contact pin extending within said body, one of saidconnectors being centrically located in the end plate, the remainingconnectors being positioned in said wall in a plane passing through boththe wall slot and the wall axis; a cylindrical member with one endengaging the cover plate recess, the other end of the cylindrical memberbeing conically shaped with a hole in the apex thereof for engaging thecontact pin of the end plate connector; and a slidable assemblysupported within said body including an operating handle with one endextending through the wall slot, and a movable contact arm fastened tothe opposite handle end and slidably engaging said cylindrical memberfor selectively making with the respective projecting contacts of thewall connectors.

6. A multiposition switch for selectively connecting a plurality ofcoaxial lines comprising a hollow body having a cylindrical wall with alongitudinal slot therein, and an end plate closing one end of saidwall, a plurality of coaxial connectors for coupling said switch to therespective lines, each of said connectors having a projecting contactpin extending within said body, one of said connectors being centricallylocated in the end plate, the remaining connectors being positioned insaid wall in a plane passing through both the wall slot and the wallaxis, a cylindrical member ccaxially located Within said body, and

7 e' sndabie assembly supported within said body 'upoii said cylindricalmember and including an secretin handle withone end extending throughthe wall slot 'anda movable contact arm for se l'ect-iyely making withthe respective projecting contact pins of the wall connectors, one endof said contact arin being fastened to the opposite end or said handle,the other arm end having a recess therein for engaging selectively the-re i sp'ectiveiwail connector c'on'tact pins'as a "detent,

and spring loop interposed between said arm ends to insure adequatecontact pressure.

3. A rndltiposition switch for selectively-connecting a plurality ofcoaxial lines comprising a hollow body having two end plates, each witha 'taperedaper'ture centri'cally located in the inner surface thereof,and a cylindrical wall having a longitndinal slot therein and endsclosed by the respective end plates, a plurality of coaxial connectorsfor coupling said switch to the respective lines, each of saidconnectors having a projectingcon-tact pin extending within said body,one of said connectors being centrically located in the tapered apertureof each of the respective end plates, the remaining connectors beingpositioned in said wall in a plane passing through both the wall slotand the wall axis, a cylindrical member having conically shaped ends,each with a hole in the apex thereof for'engaging the contact pin ofthe-respective end plate connectors, a 'slidable assembly supportedwithin said body by the cylindrical members,said assembly including anope-rating handle with one end extending through the wallslot, a movablecontact arm for selectively making with the respec-'- tive projectingcontact pins of the Wall connectors, one end of said contact armsbeingfastened to the opposite end of said handle, the other armend-having a recess therein for engaging the wall coring-rotor contactpins as a detent and a'spring loop interposed between said arm ends'toinsure adequate contact pressure.

8;--A mu-ltiposition switch for selectively con- 8 njecting a pluralityof coaxial lines comprising a hollow body having an'end plate with atapered aperture centrically located in the inner surface thereof, aninsulating cover plate having a recess therein, and a cylindrical Wallhaving a longitudinal slot therein and ends closed by the respectiveplates; aplufality of coaxial connectors for coupling said switch to therespective lines, each of said connectors having a projecting contactpin extending within said body, on'eof said connectors being centricallylocated in the ta-"- p'ered aperture of the end plate, the remainingconnectors being positioned in said wall in a plane passing through boththe wall slot and the wall axis; a-cylindrical member with oneendengaging the cover plate recess, the other end of the cyl-im dricalmember being conically shaped with a hole in the apex-thereof forengaging thecontact pin of the end plate connector;- and a slidab1eassembly supported within said body by the cylindrical member, said assemblyincluding an operating handle with one end extending through the wallsiot, a movable contact arm forselectively making with the rwpectiveprojecting contact pins of the wall connectors, one end of said contactarm-2s being fastened to the opposite end of said handlathe other armend having a recess therein for engaging the wall connector contact pinsas a detent and a spring loop interposed between said arm ends to insureadequate contact pressure.

GARDINER GREENE.

shenani ans CITED The following references are of record in the file ofthis patent:

"UN ITET STATES PATENTS Number Naine one 1,013,35 Hastings Feb. 20, 19121,443,098 Smith Jan. '23, 1923 1,997,158 Thomas Apr. 9, 1935 2,426,136Dow a. Au 26-, 194'?

